Digital Healthcare: Individual Engagement and IT-Enabled Design

Thesis (Ph.D.)--University of Washington, 2021In this dissertation, I study the transformational effect of information technology on healthcare. I take two main perspectives to investigate the topic: individual engagement and IT-enabled design. Along the first perspective, I study individuals’ engagement process in online healthcare communities. Individuals’ engagement in online healthcare communities provides opportunities for healthcare providers to deliver services in a timely and cost-effective manner. In an aim to better understand and facilitate individuals’ online engagement, I apply econometric structural approaches to disentangle individuals’ online behavior dynamics in my first two essays. Specifically, the first essay studies individuals’ participation states that drive their self-regulatory behaviors online, and the second essay investigates individuals’ learning behaviors during their health-management process. Along the second perspective, I follow the design-science paradigm to study personalized healthcare recommendation systems in my third essay. To address several key challenges in healthcare recommendations, I propose a bandit-based recommendation framework that is enhanced by deep-learning feature engineering and diversity promotion constraint. I evaluate the proposed framework through extensive simulation experiments, and the results justify the superiority of the model as compared to a wide range of state-of-the-art recommendation systems

A New 3D Shaping Method for Low-Thrust Trajectories between Non-Intersect Orbits

This paper proposes a new shape-based method in spherical coordinates to solve three-dimensional rendezvous problems. Compared with the existing shape-based methods, the proposed method does not need parameter optimization. Moreover, it improves the flexibility of orbit fitting, greatly reduces the velocity increment and maximum thrust acceleration, and ensures the orbit safety to a certain extent. The shaping function can provide the initial estimate for numerical trajectory optimization and improve the convergence rate in a certain range when combined with the normalization method. The superiority of the proposed method over the existing methods is demonstrated by two numerical examples. Its effectiveness at initial estimation generation in the indirect optimization of a low-thrust trajectory is demonstrated by the third example

Modelling raindrop impact and splash erosion processes within a spatial cell: A stochastic approach

A new approach is proposed to simulate splash erosion on local soil surfaces. Without the effect of wind and other raindrops, the impact of free-falling raindrops was considered as an independent event from the stochastic viewpoint. The erosivity of a single raindrop depending on its kinetic energy was computed by an empirical relationship in which the kinetic energy was expressed as a power function of the equivalent diameter of the raindrop. An empirical linear function combining the kinetic energy and soil shear strength was used to estimate the impacted amount of soil particles by a single raindrop. Considering an ideal local soil surface with size of 1 m × 1 m, the expected number of received free-falling raindrops with different diameters per unit time was described by the combination of the raindrop size distribution function and the terminal velocity of raindrops. The total splash amount was seen as the sum of the impact amount by all raindrops in the rainfall event The total splash amount per unit time was subdivided into three different components, including net splash amount, single impact amount and re-detachment amount The re-detachment amount was obtained by a spatial geometric probability derived using the Poisson function in which overlapped impacted areas were considered. The net splash amount was defined as the mass of soil particles collected outside the splash dish. It was estimated by another spatial geometric probability in which the average splashed distance related to the median grain size of soil and effects of other impacted soil particles and other free-falling raindrops were considered. Splash experiments in artificial rainfall were carried out to validate the availability and accuracy of the model. Our simulated results suggested that the net splash amount and re-detachment amount were small parts of the total splash amount Their proportions were 0&middot15% and 2&middot6%, respectively. The comparison of simulated data with measured data showed that this model could be applied to simulate the soil-splash process successfully and needed information of the rainfall intensity and original soil properties including initial bulk intensity, water content, median grain size and some empirical constants related to the soil surface shear strength, the raindrop size distribution function and the average splashed distance. Copyright © 2007 John Wiley & Sons, Ltd

Understanding Physicians’ Online-Offline Behavior Dynamics: An Empirical Study

Physicians’ participation in online healthcare platforms serves to integrate online healthcare resources with the offline medical system. This integration brings opportunities for reshaping healthcare delivery systems. In the field of telemedicine, there has been an extensive discussion about physician participation, but little is known about how physicians actually participate in online healthcare platforms and offline medical systems. Understanding physicians’ participation dynamics between online and offline channels is of great importance to academic researchers, practitioners, and policymakers. Such an understanding can reveal insights into how healthcare is actually delivered to patients through both channels, how to contribute to quantifying the social impacts of online healthcare services, and how to improve healthcare delivery systems. Thus, in this study, we investigate physicians’ online-offline behavior dynamics using data from both online and offline channels to conduct our analysis. As physicians’ online and offline activities are highly endogenous, we deploy a time-series technique and develop a structural vector autoregression (SVAR) model to examine the behavior dynamics. We find that physicians’ online activities can lead to a higher service quantity in offline channels, whereas offline activities may reduce physicians’ online services due to resource constraints. Our results also show that the more offline patients physicians serve, the more articles the physicians will likely share online. These findings are robust to various econometric specifications and estimation methods. Our research advocates for the benefits Health 2.0 produces and provides evidence of the value of online healthcare communities and the policies that support them

Embedding Uncertain Temporal Knowledge Graphs

Knowledge graph (KG) embedding for predicting missing relation facts in incomplete knowledge graphs (KGs) has been widely explored. In addition to the benchmark triple structural information such as head entities, tail entities, and the relations between them, there is a large amount of uncertain and temporal information, which is difficult to be exploited in KG embeddings, and there are some embedding models specifically for uncertain KGs and temporal KGs. However, these models either only utilize uncertain information or only temporal information, without integrating both kinds of information into the underlying model that utilizes triple structural information. In this paper, we propose an embedding model for uncertain temporal KGs called the confidence score, time, and ranking information embedded jointly model (CTRIEJ), which aims to preserve the uncertainty, temporal and structural information of relation facts in the embedding space. To further enhance the precision of the CTRIEJ model, we also introduce a self-adversarial negative sampling technique to generate negative samples. We use the embedding vectors obtained from our model to complete the missing relation facts and predict their corresponding confidence scores. Experiments are conducted on an uncertain temporal KG extracted from Wikidata via three tasks, i.e., confidence prediction, link prediction, and relation fact classification. The CTRIEJ model shows effectiveness in capturing uncertain and temporal knowledge by achieving promising results, and it consistently outperforms baselines on the three downstream experimental tasks

Female CYBB Mutation Mosaicism Leading to Inheritance of X-linked Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a heterogeneous primary immunodeficiency characterized by severe bacterial and fungal infections and tissue granuloma formation early in life. Diagnosis of CGD involves the granulocyte function assays and gene mutation analysis. X-linked CGD (XL-CGD) caused by gene defects of CYBB is the most prevalent type of CGD. The clinical data and gene characteristics of a rare female X-chromosome mosaicism leading to inheritance of XL-CGD were reported here. The patient is a 7-year-old boy manifested as recurrent lower respiratory tract infection and failed to thrive. The patient had a history of osteo- myelitis and perianal abscess, with Bacille Calmette-Guérin (BCG) vaccine complications. Respiratory burst of neutrophils was measured with DHR oxidation assay and the histogram showing no significant change in neutrophil fluorescence after stimulation of the patient and the mother's histogram had a pattern of 2 peaks after stimulation. A heterozygous mutation in the CYBB gene (c.866G > A, p.W289X) was identified through inheritance from the patient's mother. Genetic analysis from blood and cheek mucosal cells indicated the female was a mosaicism in CYBB with mutation was present in about 19.5% of her leukocytes. We reported the clinical data and gene characteristics of a rare female X-chromosome mosaicism leading to inheritance of XL-CGD for the first time in China to enrich the understanding of XL-CGD and provide new sights for the hereditary counseling

Multidisciplinary Optimization and Analysis of Stratospheric Airships Powered by Solar Arrays

Stratospheric airships have much potential in military and commercial applications. Design, analysis and optimization of stratospheric airships involves complex trade-off of different disciplines, and hence a multidisciplinary approach is essential. This paper describes a methodology coupling several disciplines and involving seven design variables to obtain the optimal design of a stratospheric airship powered by solar arrays. A numerical method is established to calculate the output power of the solar array in the optimization process. The optimal solutions are obtained using hybrid algorithms. The methodology can obtain the optimal envelope shape, solar array layout and other general configurations of subsystems. Results show that the methodology was able to achieve a solution with a 19.2% reduction in airship volume compared to the value being part of an arbitrary initial set of airship parameters. In addition, a comparative study is carried out to highlight the importance of considerations of solar array layouts and array circumferential location. Furthermore, detailed sensitivity analysis shows that operating parameters of latitudes, heading angles and average resisting wind speeds have significant effects on the airship design and solar array layouts

Dietary Effect of <i>Brevibacillus laterosporus</i> S62-9 on Chicken Meat Quality, Amino Acid Profile, and Volatile Compounds

Probiotics are being used in diets to improve the quality of chicken meat. The aim of the study was to investigate the effects of dietary supplementation with Brevibacillus laterosporus S62-9 microbial agent on the meat quality, amino acids, and volatile compounds of chicken. The experiment was carried out with 160 1-day-old Arbor Acres male broiler chickens, rearing for 42 d. The chickens were randomly divided into two groups of 8 replicates each, with 10 chickens in each group. No supplement was added to the basal diet in the control group and Brevibacillus laterosporus S62-9 microbial agent was added to the diet of the experimental group. At the end of the experiment, the meat quality, meat chemical composition, amino acid composition, and volatile compounds of chicken were determined. The results showed that pH (p p p p p p Brevibacillus laterosporus S62-9 microbial agent can be used as a novel and effective feed supplement to improve the nutritional quality and flavor characteristics of broilers

Improved Ionosonde Monitoring of the Sporadic E Layer Using the Frequency Domain Interferometry Technique

The sporadic E (Es) layer is a thin layer of ion plasma enhancement in the E-region ionosphere, typically at altitudes of 90&ndash;120 km with vertical and horizontal extent of several or several tens of kilometers. As the transition region between the lower and upper atmosphere, this layer is of critical importance for ionospheric studies. The most economical but effective method to observe this layer is using ionosonde, which, however, is incapable of capturing the finer structure or the internal inhomogeneity of the Es layer as the range resolution is on the order of kilometers. To overcome this limitation, we employ the frequency domain interferometry (FDI) technique, a technique that has been successfully applied to the analysis of some radar and sonar measurements. Here, we use the Es layer measurements near Wuhan, China (114&deg;22&prime;E, 30&deg;30&prime;N) on 8 June 2021 as examples to showcase the capability of this technique. Our results show that the spatial resolution of ionosonde imaging is remarkably increased: the complexity of the internal fine structure in the Es layer can be well observed in the FDI-processed ionograms, whereas the intrinsic range resolution is several kilometers. Moreover, by comparing the ionograms obtained with and without the FDI technique, it is found that the FDI-processed ionogram is particularly suitable for the observation of evolutional processes in the Es layer, as well as the identification of different types of Es layer. With this level of spatial resolution, ionosonde, in combination with the FDI technique, opens the possibility for more refined observations of the Es layer